Preheat the oven to 170c/325f. Line a 20cmx20cm baking tin with baking parchment.
Cream the butter and sugar together, add in the egg and vanilla extract and stir until combined. Add in the flour and baking powder and thoroughly mix.
Spoon the mixture into the prepared baking tin (it should be a thick mixture). Spread it out so it reaches the edges.
Arrange the chunks of chocolate caramel on top of the blondie mixture, push them in a little with your finger.
Spoon the Nutella onto the mix in about 10 blobs. Use a cocktail stick or a knife to give the Nutella a bit of a swirl around. Place in the oven and cook for 35-45 mins - until an inserted skewer comes out clean. Place some foil on top after 25 minutes if the top starts to look too brown.
Remove from the oven, leave to cool in the tin for a couple of minutes before removing from the tin and placing on a cooling rack to cool further. Remove baking parchment and slice before serving.
Notes
* You could also use Cadbury caramel chunks or any other soft-caramel filled chocolates..Nutritional Information is per serving.